The present invention relates to a bearing bush and a method of manufacturing the same, which bearing bush has a seam and is of an integral structure suitable for use in, for example, a turntable in a microwave oven for the purpose of bearing a thrust load as well as a radial load.
For example, U.S. Pat. No. 4,437,214 discloses a method of manufacturing a bearing bush which is unitary and is not provided with any seam and which has an inwardly extending flange without any seam. This prior bearing bush is formed only by drawing.
As seen from FIGS. 1-7 of the above patent, an annular groove (2) is formed in a unitary circular plate to facilitate manufacture, and the circular plate is subjected to drawing by means of a die (7) and a punch (8) in a similar manner to the manufacture of pots. As shown in FIG. 4 of the patent, the bottom is partly punched by a punch (15). However, such method is disadvantageous for the manufacture of a multi-layered bearing in that an inner peripheral layer of a soft bearing alloy and an outer peripheral layer of a hard steel back layer will become separated from each other at the interface therebetween to cause cracking in the bearing alloy, thus resulting in reduction in accuracy of surface working and out of roundness and misalignment of a bearing bush and a rotating shaft. Accordingly, finished multi-layered products according to the patent are unsatisfactory.